Drainage rate of cellulosic papermaking slurries



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3,008,868 DRAINAGE RATE OF CELLULOSIC PAPERMAKING SLURRIES David A. Feigley, Jr., and Leonard N. Ray, Jr., Manor Township, Lancaster County, Pa., assignors to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania No Drawing. Filed Dec. 23, 1957, Ser. No. 704,356 16 Claims. (Cl. 162-179) This invention relates generally to cellulosic fibrous sheets and more particularly to water-laid cellulosic fibrous sheets such as paper and felt. Still more particularly, the invention relates to the improvement in the 7 drainage rate of cellulosic papermaking stocks.

In papermaking processes, it is always relatively simple to slow the drainage rate of a stock. This is most readily accomplished by mechanical refining of the fibers in a beater, Jordan engine, disc refiner, or the like. In-

creasing the drainage rate, however, is a more ditficult Cellulosic bers Water Add polvvalent metal ion Add polymerized fatty acid salt Far t-d raining slurry It is the primary object of the present invention to present a process which will produce a dramatic decrease in the drainage time of a cellulosic papermaking stock without the necessity of coating the individual .fibers with a substance such as a rubber which produces a sheet having vastly diiferent properties from a sheet prepared from uncoated fibers. It is a further object of the present invention to present a process whereby a smoother sheet possessing greater flexibility and water resistance may be prepared in contrast with a sheet prepared by prior known processes.

These objects are accompanlished in a surprisingly effective and straightforward manner. The invention contemplates improving the drainage rate of a cellulosic papermaking stock by treating the cellulosic fibers in the stock with a polyvalent metal ion selected from the group consisting of Al+++, Cr+++, Fe+++. Subsequent to the polyvalent metal ion treatment, there is added to the stock a water-soluble salt of an organic, aliphatic, polycarboxylic acid containing at least 36 carbon atoms.

The cellulosic fibers contemplated for treatment by the present invention are those cellulosic fibers normally used in papermaking. As examples of such fibers, there may be given sulfite pulp, kraft, soda pulp, cotton aids, cotton linters, rags, and newsprint. The stock is formed by known methods wherein the fibers are suspended in water to a workable consistency, using in the range of about O.5-5%. Normally, a stock of the proper consistency is subjected to mechanical refinement until the desired degree of freeness is obtained. The precise freeness will be determined by the kind of paper or felt to be produced. Glassine papers, for example, call for the production of a stock with a Canadian freeness below 50 and usually above zero. Nonglassine papers papers call for a faster draining stock. The caliper or gauge of the paper or felt to be produced will also control to a large degree the freeness to which the stock is refined. In the prment process, however, the freeness may be taken substantially below that which normally is needed to produce the particular sheet desired. Subsequent treatment to be described below will raise the freeness again to that needed to run the paper machine at normal speeds to produce the desired paper of the proper gauge. This feature of being able to take the stock to a lower freeness than that needed is responsible for the production of a smoother sheet having greater flexibility than would be obtainable if the lower freeness could not be used. Alternatively, the stock may be beaten or otherwise refined to the usual freeness. The subsequent treatment will raise the freeness above that which normally must be used and will thus allow an increase of machine speed or the production of a thicker sheet. It will be apparent that this control of the stock freeness can be carried out in varying degrees.

The cellulosic fibers in the stock are then treated with either aluminum, iron, or chromium ion in the trivalent state. Such treatment may be accomplished by the mere addition of an aluminum, ferric, or chromic salt to the stock. Mixtures thereof can be used. Preferably, however, the salt is taken up in water and added to the stock in the form of a solution. The addition of a solution expedites the distribution of the metallic ion throughout the water phase of the stock and eliminates the need for waiting for the salt to dissolve in the water phase of the stock itself.

The amount of metallic ion to be added to the stock need not be large. As a general rule, about 0.1% by Weight of the metal based on the dry weight of the fibers being treated is ample to render the fibers amenable to subsequent reaction with the organic acid salt. Stated another way, the metallic salt should be added in an amount of about 1-5 by weight of the salt based on the dry weight of the fibers being treated. Such amounts of the salt will always supply sufiicient ion to successfully pretreat the cellulosic fibers. Larger amounts of the salt above that amount stated will do no actual harm to the stock. However, in the interest of avoiding waste of the metallic salt, it is preferred that the amount of the salt be kept within the stated range of 1-5 by weight of the salt based on the dry weight of the fibers. If too large an amount of the salt is introduced into the stock, an insoluble soap may be formed on subsequent addition of the organic acid salt. This situation will produce a further waste of the acid and, from this standpoint, is undesirable.

Any salt of aluminum, iron, or chromium may be used so long as the salt is reasonably soluble in water and the metal is in the trivalent state. The nitrate, sulfate, and chloride are the commonest soluble salts of aluminum, iron, and chromium. Papermakers alum is the salt of choice.

Although the metallic ion has been described as added to the slurry subsequent to the mechanical refining step, such point of addition is not critical. Actually the metallic ion in the form of a salt may be added to the stock at any time during the formation of the stock. Thus it may be added prior to the time at which the stock is mechanically refined. If this be done, the stock will be ready for the addition of the polycarboxylic acid salt as soon as the proper degree of refinement has been obtained.

. 'Following treatment of the stockwith the polyvalent metal ion, the cellulosic fibers are then in condition to be reacted with the organic acid salt.

.The acids suitable for use in the present invention are best illustrated by the dimerized andtrimerized fatty acids which are readily available in commerce. These acids are prepared by the thermal polymerization of drying oil acids carried out in a' pressure vessel in the presence of water in the form of steam. The resulting compositions generally contain on the average of about 3 monomer, 75% dimer, and 22% trimer. known as dimerized fatty acid and will have an iodine Value of approximately 90 and an acid number of approximately 190. The dimerized acid itself is essentially a 36-carbon dicarboxylic acid obtained by dimerization of the linoleic acid of soya, cottonseed, corn, and linseed oils of commerce; it possesses olefinic unsaturation, ,The product is frequently referred to as 'dilinoleic' 'acid; This dimerized acid product may be purchased under the ."name Empol 1022." It is apparent that the dimerized acids and the trimerized acids resulting from the above-described pressurized process may be separated or further concentrated as desired. Thus the trimer acid maybe purchased as such.- The trimer acid is 54-carbon acid and contains a plurality of carboxylic acid groups. As a further variation on the dimer and trimer acids, any residual olefinic unsaturatio'n in the carbon chain may be eliminated by hydrogenation. The hydrogenated dimer acid may be purchased under the name Emery 3020-8; the predominantly straight trimer acid may be purchased under the name Emery 3055-8. In addition to the Such a product is above-described acids themselves, there may also be used 7 as ammonia, sodium hydroxide, potassium hydroxide,

carbonates of ammonia, sodium and potassium and even organic amines.

solubleto be operable. The compounds are used in relatively small amounts compared. with the amount of water present, so easy solubility is not necessary. I n'the present specification and. claims, it is contemplated that the Idefined organic polycarboxylic acids'are rendered watersoluble where necessary by reaction of the acid with .a

solubilizing alkaline ingredient to form 'a salt. Thus the compound to be used will be selected from the group consisting ofwater-soluble polycarboxylic acids, Watersoluble polycarboxylic acid salts, and mixtures thereof.

, As is the case with the metallic salt, the polycarboxylic acid salt need not be added in large amounts. Amounts of the polycarboxylic acidsalt in the range of about 1-5 by ,weight polycarboxylic ,acid based on the dry weight of the 'cellulosic fibers is the broad range, with the preferred amount running about 3% by weight acid based on the weight of the fibers. Amounts smaller than about 1% by. weight donot bring about a significant improvement in the, drainage rate, while amounts larger than about 5% by weight are generally wasted since the exc'ess simply remains in the white water. 7

The actual step of adding the organic polycarboxylic salt will first be taken up in water to form an aqueous means in which the present invention has not been used; 1

to someextent with alkaline earth metal compounds and M It must be emphasized that the compounds used in the present invention need not be very solution or suspension and the salt will be added in the form of that solution or suspension. Use of a solution aids in quick dispersion of the water-soluble polycarboxylic acid throughout the stock and hastens the .reaction that takes place between the polycarboxylic acid Once the polyy 1 carboxylic acid salt has been-added tothe stock, preferably-with gentle agitation, reaction will be complete normally within 15 minutes and iusually wit hin about 5;] minutes. The, freeness of the'stock'asycompared' with identical untreated stock will, be found to have increased g as much as 70%. Stated another way, the rate of 9 age of the stock will be found to be about half that of h identical untreated stock, and frequently the drainage time will be reduced to'appreciably less than half of that l and the surface of the eel'lulosic fibers.

of the untreated stock.

The reason for theimproved: drainage rate obtained by the present; invention j is not clearly understood. postulated'that thfe. additioni of the polyvalent metal ion brings about a reversal of the charge carried by-thej cellulosic fibers in waterlsuspension. ,rThischarge versal allows the treated. fibers to react with the watcr-jf soluble polycarboxylic acid toproduce afiber having a modified surface, which modified surface apparently brings aboutth'e improved" drainage rate: .I t is rate; noted that mere-treatment or the cellu'losic fibers in water suspension with the polyvalent metal ions does not change It is the drainage characteristics of the stock significantly. An

attempt to react. the 1 eellulosic fibers-with polycarboxylic 7 acid salts without prior treatment withpolyvalent metallic ions does not'producejany change in the drainage haracteris'tics'of the stock. Furth'ermore, treatment a of A, the cellulosic fibers with aluminum, ferric, or chromic ion followed by an attempt to react the treated fibers with an organic acid containing less than 36 carbon atoms willQ produce a stock having drainage characteristics substan- I l tially worse than that of the dimersoap-treated stock.

Stocks treated by the present invention may then be handled as any other papermaking stock in the production of useful products such as various papers and felts.

Papers produced by the present process possess increased flexibility and hence increased resistance to breakage and tearage when compared withsimilar'pap'ers prepared by The usual sizing agents such as starch, casein, and cellulose drums may be used in conjunction with the sheet- Sizing and other f processing variables may be carried; out after the fibers V have been treated and before the treated slurry is passed to the wire, or once the sheet has been formed 'on the m For certain purposes it may be desirable to; precipitate synthetic rubber .binder onto the cellulosidfibers to strengthen the sheet; Small amounts, generally 1-5% by weight rubberbasedon the weightcf the fibers, l will usuallysuffice for, this purpose. Mere. addition ofthe latex to the. treated stock followed by agitationwill caus'e precipitation of this small amount of rubberonto, the fibers. Where larger amounts of rubber are to Q U added, addition of .aprecipitating agent, such as a solu tion of-papermakers. alum, willspeed-andcomplete the making processes described herein.

wire.

rubber precipitation. The synthetic rubbers which can be used are those used in' beater saturation processes and include 'butadiene-styrlene copolymers, butadiene-acr ylo;

nitrile copolymers, polychloroprene; and the like.

The following examples illustrateseveral embodiments 1 l i of the invention.

. All Parts by weight .unless other wisestated. i 1 i 1 I E rample minutes]. The Canadian 3-gram freenessjof the resulting oratorysheetmoldis 29 seconds To alstockprepar stock is 370 cc. and the drainage time in a 12" x lZf'labexactlyas described aboveftherei .is added one part papermakers alum dissolved'in parts of water, with gentle agitation. There is then added a soap solution sufiicient to supply 1.5 parts of a hydrogenat'ed dimer acid (hydrogenated dilinoleic acid, Emery 3020-8). The soap solution is prepared by placing the 1.5 parts of the dimer acid into 50 parts of water and adding sufficient potassium hydroxide to dissolve the acid.

The Canadian 3-grams freeness of the treated stock was 570 cc. and the drainage time in the laboratory 12" x 12" sheet mold was 13 seconds. The resulting sheet was dried in an air circulating oven maintained at 195 F. and proved to be smoother than an identical sheet made from stock not treated with the metallic ion and polycarboxylic acid soap. The sheet also was significantly more flexible and possessed greater water resistance than an untreated sheet.

Example II Example I was repeated save that in place of the alum solution there was used a solution of ferric chloride prepared by dissolving one part of the salt, FeCl -6H O, in 100 parts water. After the soap treatment the stock had a Canadian freeness of 480.

Example III Example I is repeated except that the potassium salt of a predominantly straight trimer acid (Emery 3055S) was used. The resulting stock has a Canadian freeness of 510.

Example IV Example I is repeated with cotton aids as the cellulosic fiber and the potassiumsoap of dimerized acid (Empol 1022) as the organic salt. The untreated stock has a Canadian freeness of 300 cc., whereas the treated stock has a Canadian freeness of 50 cc.

Example V Example I is repeated using newsprint as the cellulosic fiber. An improvement in Canadian freeness from 250 to 420 is noted.

We claim:

1. In a papermaking process wherein a stock comprising papermaking cellulosic fibers suspended in water is formed into a sheet on a papermaking machine, the improved process of improving the drainage rate of said stock which comprises treating said cellulosic fibers in said stock with a polyvalent metal ion selected from the group consisting of Al+++, Cr+++, and Fe+++, and adding to the treated stock a water-soluble salt of an organic, aliphatic, polycarboxyl-ic, polymerized fatty acid containing at least 36 carbon atoms.

2. A process according to claim 1 wherein said metal ion is aluminum.

3. A process according to claim 1 wherein said polycarboxylic acid is a saturated acid.

4. A process according to claim 1 wherein said polycarboxylic acid is an unsaturated acid.

5. A process according to claim 1 wherein said polycarboxylic acid is added in amount of about 15% by weight acid based on the dry weight of said cellulosic fibers.

6. A method according to claim 1 wherein said polycarboxylic acid comprises dilinoleic acid.

7. A process according to claim 1 wherein said polycarboxylic acid contains 54 carbon atoms.

8. A process according to claim 1 wherein said watersoluble salt of an organic polycarboxylic acid comprises the potassium salt.

9. A process of forming a sheet which comprises forming in water a slurry of cellulosic fibers, treating said cellulosic fibers with a polyvalent metal ion selected from the group consisting of Al+++, Cr+++, and Fe+++, adding to the treated slurry a water-soluble salt of an organic, aliphatic, polycarboxylic, polymerized fatty acid containing at least 36 car-hon atoms, and forming a sheet from the thus treated slurry.

10. The process according to claim 9 wherein said polyvalent metal ion comprises aluminum and said watersoluble salt of a polycarboxylic acid comprises the potassiurn salt of hydrogenated dilinoleic acid.

11. A water-laid sheet comprising cellulosic fibers whose surfaces are reacted with an organic, aliphatic, polycarboxylic, polymerized fatty acid containing at least 36 carbon atoms.

12. A sheet according to claim 11 wherein said polycarboxylic acid contains 54 carbon atoms.

13. A sheet according to claim 11 wherein said polycarboxylic acid comprises a saturated acid.

14. A sheet according to claim 11 wherein said polycarboxylic acid comprises an unsaturated acid.

15. A sheet according to claim 11 wherein the surfaces of said cellulosic fibers are reacted with about 15% by weight of said polycarboxylic acid based on the total weight of said fibers.

16. A sheet according to claim 11 wherein said polycarboxylic acid comprises dilinoleic acid.

References Cited in the file of this patent UNITED STATES PATENTS 1,958,202 Novak May 8, 1934 2,447,064 Gebhart et al Aug. 17, 1948 2,473,798 Kienle et al. June 2, 1949 2,665,206 Bradley Jan. 5, 1954 2,665,207 McMillan et al. Jan. 5, 1954 2,666,699 McQuiston et al. Jan. 19, 1954 2,731,481 Harrison et a1 Jan. 17, 1956 2,772,970 Feigley Dec. 4, 1956 2,812,342 Peters Nov. 5, 1957 2,887,431 Piersol May 19, 1959 2,930,106 Wrotnowski Mar. 29, 1960 2,940,892 Feigley et al. June 14, 1960 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No, 3 0083368 November 14 1961 David A, Feigley Jr. 9 et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 61 for "accompanlished" read accomplishe column 2, line 11 for "above" read about same line 11, strike out "papers", second occurrence; column 5 line 8 for "3- grams" read 3-gram Signed and sealed this 24th day of April 1962,

(SEAL) Attest:

ESTON G1 JOHNSON DAVID L 0 LADD Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No, 3 0083368 November 14 1961 David A, Feigley Jr. 9 et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 61 for "accompanlished" read accomplishe column 2, line 11 for "above" read about same line 11, strike out "papers", second occurrence; column 5 line 8 for "3- grams" read 3-gram Signed and sealed this 24th day of April 1962,

(SEAL) Attest:

ESTON G1 JOHNSON DAVID L 0 LADD Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 3,008,868 November 141 1961 5 '2 David A. Feigley Jr. et al.

It is hereby certified that error appears in the above numbered patent requiring correction an corrected below.

d that the said Letters Patent should read as Column 1, line 61 for "accompanlished" read accomplished; column 2, line l1 for ,above read about same line 11, strike out "papers", second occurrence; column 5 line 8, for "ii-grams? read 3-gram Signed and sealed this 24th day of April 1962.

(SEAL) Attest:

ESTON JOHNSON DAVVID no LADD Attesting Officer Commissioner, of Patents 

1. IN A PAPERMAKING PROCESS WHEREIN A STOCK COMPRISING PAPERMAKING CELLULOSIC FIBERS SUSPENDED IN WATER IS FORMED INTO A SHEET ON A PAPERMAKING MACHINE, THE IMPROVED PROCESS OF IMPROVING THE DRAINAGE RATE OF SAID STOCK WHICH COMPRISES TREATING SAID CELLULOSIC FIBERS IN SAID STOCK WITH A POLYVALENT METAL ION SELECTED FROM THE GROUP CONSISTING OF AL+++,CR+++, AND FE+++, AND ADDING TO THE TREATED STOCK A WATER-SOLUBLE SALT OF AN ORGANIC, ALIPHATIC, POLYCARBOXYLIC, POLYMERIZED FATTY ACID CONTAINING AT LEAST 36 CARBON ATOMS. 